Update .devcontainer/Dockerfile

Add license header

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: waybackarchiver

.devcontainer/Dockerfile

@@ -1,3 +1,7 @@
+# Copyright 2022 Wayback Archiver. All rights reserved.
+# Use of this source code is governed by the GNU GPL v3
+# license that can be found in the LICENSE file.
+
 # See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.195.0/containers/go/.devcontainer/base.Dockerfile
 # [Choice] Go version (use -bullseye variants on local arm64/Apple Silicon): 1, 1.16, 1.17, 1-bullseye, 1.16-bullseye, 1.17-bullseye, 1-buster, 1.16-buster, 1.17-buster
 ARG VARIANT=1-bullseye